This invention pertains to milling machines, in general, such as are used to mill or grind material, the same having inter-engaging rolls, and in particular to a roll arrangement, and an inter-roll drive, for a milling machine.
Known roll milling machines typically incorporate a single, inter-roll drive on one common end of the opposing rolls. Common designs comprise belt inter-roll drives, or single gearbox inter-roll drives. Inter-roll drive provide a differential speed between the opposing rolls of the roll milling machine to enhance grinding. In prior art machines, one of the opposing rolls is spring-loaded at each end for protection from tramp metal, rocks, or other foreign material in the feed of the material being ground. When fine grinding at high horsepowers, the forces of the single, inter-roll drive at the one common end of the rolls causes an uneven roll nip gap at a given end of the rolls. The forces of the single-ended, inter-roll drive cause the spring-loaded roll to move like a lever, with its drive-end bearing serving as the pivot. To date, no satisfactory solution for this problem has been proposed.
Further, prior art roll milling machines incorporate a belt-type inter-roll drive which provides the differential speed between the opposing rolls. A common drive consists of a drive sheave, a driven sheave, one or more idler sheaves, and a tension mechanism. A belt or belts gird the sheaves in what is referred to as a serpentine drive. The prior art tension mechanisms, however, are difficult to disassemble and reassemble, for the purposes of belt removal and replacement.
The foregoing illustrates limitations known to exist in present inter-roll drive milling machines. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.